The antiviral agents AZT, DDC and interferon alpha were evaluated for their effectiveness against HIV by PCR. Briefly, H9 and U937 cells were infected with cell-free HIV-1, after which the drugs were added into the culture at specified concentrations: AZT 50 ug/ml and rIFNa at 50 units/ml or in combination at the same concentrations. Genomic DNA and RNA were analyzed by PCR using primers to the gag region(SK38/39). Virus production was measured by RT and p24 antigen assays. Greater than 95% inhibition of HIV replication was observed with AZT and the combination of AZT and rIFNa from 3-4 days after infection using the p24 and RT assays in both H9 and U937 cells. Viral DNA and RNA synthesis were not significantly inhibited by rIFNa. Some inhibition of DNA and RNA was observed with AZT alone followed by a recovery of viral nucleic acid with time. More than 80% inhibition of viral DNA synthesis was observed with the combination of AZT and rIFNa. Viral RNA was undetectable in both infected H9 and U937 cells in the presence of AZT and rIFNA combined. DDC was similarly evaluated using infected H9 and U937 cells. Treatment with concentrations of 0.5 amd 1uM resulted in greater than 95% inhibition of HIV DNA on both target cells. AZT and DDC alone at the higher concentration inhibited viral DNA and RNA synthesis in cells and in supernatant, but significant toxicity was noticed (60-70% viable cells). Combination treatment with either AZT or DDC and rIFNa at lower doses resulted in significant inhibition of HIV DNA and RNA synthesis in cells and RNA in supernatants, with minimal toxicity (95% viability) in the treated cultures. In other studies, a spectrum of compounds that inhibit gp120 binding to CD4 including aurin tricarboxylic acid, DO26 and DR79 were found to inhibit HIV replication as measured by p24 antigen values and DNA PCR. In other experiments, inhibitors ODC, tyrosine kinase, divalent metal chelators, integrase, protease, RT, DNA primase and gyrase are being evaluated in vitro for anti-HIV activity. The molecular mechanism of this inhibitory effect will be studied by analyzing the expression of various 1 host genes in response to drug treatment.